P75 ECU Technical Reference
Technical reference for the Acura Integra P75 ECU, covering hardware variations, OBD2 specifications, and compatibility with OBD1 systems.
The P75 ECU is the factory engine control unit for the 1996â2000 Acura Integra LS/GS (B18B1 engine). While primarily an OBD2-based unit, it shares significant architecture with the OBD1 P74 ECU.
Overview
The P75 is designed for non-VTEC B-series engines. It manages fuel and ignition mapping optimized for the B18B1 platform.
Note
For information regarding the OBD1 variant of this ECU, refer to the P74 documentation0.
Hardware Variations
The P75 underwent several revisions throughout its production cycle to accommodate changes in OBD2 emissions standards and internal board layouts.
| Revision | OBD Version | Chassis Years | Notes |
|---|---|---|---|
| P75-A01 | OBD2a | 1996â1998 | Standard LS/GS mapping |
| P75-A02 | OBD2b | 1999â2000 | Updated processor and emissions logic |
Compatibility
The P75 is frequently used in engine swaps due to its robust, non-VTEC management.
Important
When converting between OBD1 and OBD2, ensure the use of a proper conversion harness. The P75 requires specific sensor inputs (such as the CKF sensor) when running in an OBD2 environment that are not present on OBD1 chassis.
Diagnostic Resources
For troubleshooting specific engine management issues, utilize the following tools:
Resistor Color Code Reference
Use the color bands on through-hole resistors to identify their resistance value before installing ECU jumpers, pull-ups, voltage dividers, or sensor-scaling parts.
How to Read the Bands
| Resistor Type | Band 1 | Band 2 | Band 3 | Band 4 | Band 5 |
|---|---|---|---|---|---|
| 4-band | 1st digit | 2nd digit | Multiplier | Tolerance | - |
| 5-band | 1st digit | 2nd digit | 3rd digit | Multiplier | Tolerance |
Color Values
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | x1 | - |
| Brown | 1 | x10 | +/- 1% |
| Red | 2 | x100 | +/- 2% |
| Orange | 3 | x1,000 | - |
| Yellow | 4 | x10,000 | - |
| Green | 5 | x100,000 | +/- 0.5% |
| Blue | 6 | x1,000,000 | +/- 0.25% |
| Violet | 7 | x10,000,000 | +/- 0.1% |
| Gray | 8 | x100,000,000 | +/- 0.05% |
| White | 9 | x1,000,000,000 | - |
| Gold | - | x0.1 | +/- 5% |
| Silver | - | x0.01 | +/- 10% |
| No band | - | - | +/- 20% |
Common ECU Examples
| Value | 4-Band Code | Typical Use |
|---|---|---|
| 220 ohm | Red, Red, Brown, Gold | LED/current-limiting or ECU hardware mods |
| 1k ohm | Brown, Black, Red, Gold | Pull-up, jumper, and driver-bias circuits |
| 1.2k ohm | Brown, Red, Red, Gold | Driver-bias circuits such as IACV repair references |
| 4.7k ohm | Yellow, Violet, Red, Gold | Transistor base resistor circuits |
| 10k ohm | Brown, Black, Orange, Gold | Pull-up, pull-down, and sensor-divider circuits |
Tip
Always confirm the measured value with a multimeter before soldering. Old ECU resistors can be heat-discolored, and some boards use small surface-mount parts marked with numeric codes instead of color bands.